Problem: Jessica ate 4 slices of pie. Luis ate 1 slice. If Jessica ate $\dfrac{4}{8}$ of the pie, what fraction of the pie is remaining?
If 4 slices represent $\dfrac{4}{8}$ of the pie, there must have been a total of 8 slices. $\text{fraction of pie remaining} = \dfrac{\text{number of slices remaining}}{\text{number of slices total}}$ Together they ate 5 slices, which leaves 3 out of 8 slices remaining. There is $\dfrac{3}{8}$ of the pie remaining.